Putrefaction

Whenever a player casts a green or white spell, that player discards a card.

Yawgmoth's Edict

Whenever an opponent casts a white spell, that player loses 1 life and you gain 1 life.

Tidal Barracuda

Any player may cast spells as though they had flash.
Your opponents can't cast spells during your turn.

Stromgald Cabal

{T}, Pay 1 life: Counter target white spell.

Douse

Snake Pit

Whenever an opponent casts a blue or black spell, you may create a 1/1 green Snake creature token.

Squallmonger

{2}: Squallmonger deals 1 damage to each creature with flying and each player. Any player may activate this ability.

Insight

Whenever an opponent casts a green spell, you draw a card.

Vernal Equinox

Any player may cast creature and enchantment spells as though they had flash.

Ifh-Bíff Efreet

Flying
{G}: Ifh-Bíff Efreet deals 1 damage to each creature with flying and each player. Any player may activate this ability.

Scandalmonger

{2}: Target player discards a card. Any player may activate this ability but only as a sorcery.

Wishmonger

{2}: Target creature gains protection from the color of its controller's choice until end of turn. Any player may activate this ability.

Llawan, Cephalid Empress

When Llawan, Cephalid Empress enters, return all blue creatures your opponents control to their owners' hands.
Your opponents can't cast blue creature spells.

Sisay, Weatherlight Captain

Sisay, Weatherlight Captain gets +1/+1 for each color among other legendary permanents you control.
{W}{U}{B}{R}{G}: Search your library for a legendary permanent card with mana value less than Sisay's power, put that card onto the battlefield, then shuffle.

Tidal Control

Cumulative upkeep {2} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Pay 2 life or {2}: Counter target red or green spell. Any player may activate this ability.

High Seas

Red creature spells and green creature spells cost {1} more to cast.

Well of Knowledge

{2}: Draw a card. Any player may activate this ability but only during their draw step.